Faculty Publications

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Publications by NITK Faculty

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Author: search.filters.author.Chiranjeevi, K.Subject: search.filters.subject.sustainability

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    Optimization and Characterization of Ferrochrome and Recycled Concrete Aggregate Mixes for Pavement Base Layers
    (American Society of Civil Engineers (ASCE), 2025) Chiranjeevi, K.; Kumar, D.H.; Yatish, R.G.; Mulangi, R.H.; Ravi Shankar, A.U.
    Utilizing alternate aggregates is crucial for conserving resources, promoting sustainability, and managing waste effectively. The focus of the current study was the utilization of ferrochrome aggregate (FCA) and recycled concrete aggregate (RCA) in cement-treated base layers with the objective of entirely replacing natural coarse aggregate (NCA). The study meticulously prepared cement treated recycled and ferrochrome aggregate (CTRFA) specimens with 3%, 5%, and 7% cement content. These specimens incorporated varying blends of RCA and FCA, ranging from 0% to 100%. Response surface method (RSM) was used to optimize the mixes by considering strength and durability criteria for cement treated bases (CTB). Microstructural characterization was aimed to explore aggregate surface roughness, mortar hardness, mineral phases, cracks, and elements within the matrix. The outcomes of optimization revealed that the optimal mixture, meeting the specifications of the Indian Road Congress, could be achieved by substituting 61% RCA and 39% FCA with 4.8% cement content. © 2024 American Society of Civil Engineers.
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    Optimizing Ball Milling for High-Quality Recycled Aggregates: Examining the Mechanical Processing and Performance of Cement-Treated Bases
    (American Society of Civil Engineers (ASCE), 2025) Chiranjeevi, K.; Ramagiri Girish, Y.; Hemanth Kumar, D.; Mulangi, R.H.; Ravi Shankar, A.U.
    Producing superior-quality recycled aggregates from demolition waste is challenging. Over the years, mec hanical treatment methods for removing attached mortar from aggregates have evolved significantly. The studies on effective recycled coarse aggregate (RCA) processing with optimized processing parameters using ball milling and characterization of processed RCA (RCA) are limited. In this study, central composite design in the response surface method was employed to optimize control process factors (charge, revolution time, and aggregate weight) with aggregate properties as responses (percentage mortar removal, water absorption WA, specific gravity Sg, impact value IV, and abrasion value AV). The aggregate processed with optimized processing parameters exhibited superior quality with enhanced physical properties. The effect of the processing of RCA on the mechanical properties of cement-treated bases was studied by utilizing processed RCA in cement-treated recycled concrete aggregate mixes. The microstructural analysis was performed using 3D-surface topography, scanning electron microscopy, and energy dispersive spectroscopy. The test results demonstrated a 63% reduction in water absorption and an improvement in Sg, IV, and AV by 12.3%, 38%, and 23.7%, respectively. It is also found that the unconfined compressive strength and flexural strength with processed RCA are improved by 31.5% and 45.7%, respectively. Natural coarse aggregate can be completely replaced with processed RCA in cement-treated bases with the optimized processing method. © 2025 American Society of Civil Engineers.